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PubMed1996

Questionnaire on the perceptions of patients about shoulder surgery.

We developed a 12-item questionnaire for completion by patients having shoulder operations other than stabilisation. A prospective study of 111 patients was undertaken before operation and at follow-up six months later. Each patient completed the new questionnaire and the SF36 form. Some filled in the Stanford Health Assessment Questionnaire (HAQ). An orthopaedic surgeon assessed the Constant shoulder score. The single score derived from the questionnaire had a high internal consistency. Reproducibility, examined by test-retest reliability, was found to be satisfactory. The validity of the questionnaire was established by obtaining significant correlations in the expected direction with the Constant score and the relevant scales of the SF36 and the HAQ. Sensitivity to change was assessed by analysing the differences between the preoperative scores and those at follow-up. Changes in scores were compared with the patients' responses to postoperative questions about their condition. The standardised effect size for the new questionnaire compared favourably with that for the SF36 and the HAQ. The new questionnaire was the most efficient in distinguishing patients who said that their shoulder was much better from all other patients. The shoulder questionnaire provides a measure of outcome for shoulder operations which is short, practical, reliable, valid and sensitive to clinically important changes.

Adult↗
PubMed1998

[Current status of shoulder arthroscopy].

Arthroscopic and open shoulder surgery have to be combined for a successful surgical therapy of the shoulder joint. A surgeon performing open surgery only or just treating by arthroscopic measurements can not cover the full spectrum of modern shoulder surgery. Isolated diagnostic arthroscopy is rarely indicated. Far more common, diagnostic arthroscopy is combined with an operative procedure both to confirm preoperative assessment of pathology and to uncover associated lesions. The results of arthroscopic stabilisation of chronic anterior posttraumatic dislocations fail to compare with high success rates of open procedures. Better patient selection will probably be the key to improving results. In case of acute traumatic first time dislocation in young highly sportive athletes the arthroscopic repair of the isolated Bankart-Perthes lesion offers the attractive advantage of anatomic reconstruction with minimal soft tissue dissection. Further indications for arthroscopic measurements of pathologies of the glenohumeral joint are synovectomy in rheumatoid arthritis, capsulotomy of shrunk capsule in frozen shoulder and tenodesis for lesions of the long head of the biceps. The arthroscopic subacromial decompression according to Ellman is the most often and successful performed procedure at the shoulder joint and has overcome the classic Neer open acromioplasty. For smaller tears of the supraspinatus tendon the arthroscopic acromioplasty can be combined with an all arthroscopic suture repair or with an mini-open repair. Larger tears of the rotator cuff are still the domain for open reconstructive procedures. In case of associated or isolated AC-joint arthritis an arthroscopic Mumford procedure can be performed. For chronic calcific tendinitis isolated arthroscopic excision of the calcium deposit is of great value. Additionally, acromioplasty is needed for true mechanical obstruction of the subacromial space.

Acromioclavicular Joint↗
PubMed2026

Do wound protectors reduce contamination in total shoulder arthroplasty? A randomized controlled trial.

HYPOTHESIS: Cutibacterium acnes is the most frequent cause of shoulder prosthetic joint infection with skin edges as a source of wound contamination. The primary purpose of this study was to determine if the use of a wound protector device decreases the deep wound bacterial colonization in primary shoulder arthroplasty. The secondary purpose was to assess the effect of device usage on deltopectoral muscle and cephalic vein injury. METHODS: This was a prospective, randomized controlled trial. A total of 100 patients undergoing primary total shoulder arthroplasty were enrolled and randomized into 2 groups: a wound protector group and a control group. Five patients withdrew from the study, leaving 48 patients in the wound protector group and 47 controls. Three deep wound culture swabs were taken after final arthroplasty implantation. The surgeon also graded deltoid, pectoralis major, and cephalic vein injury on a 0-3 scale based on modification to the Tscherne classification of soft tissue injury. The primary outcome of this study was positive culture results for C acnes. Secondary outcomes included total bacterial culture positivity as well as soft tissue injury grades. A subanalysis removing likely contaminant positive cultures (growth >7 days and 1 colony only) was also performed. Comparisons between groups were made using Fisher exact test for categorical outcomes and t tests and Mann-Whitney U tests for continuous variables. RESULTS: The use of a wound protector did not result in any significant differences compared with controls in the rate of positive cultures for C acnes (15% vs. 21%, P = .593) or all bacteria (15% vs. 26%, P = .304). Removing likely contaminant positive cultures did not demonstrate any significant difference in culture positivity (9% vs. 17%, P = .355, for C acnes; 9% vs. 19%, P = .231, for all bacterial species). The wound protector group had better soft tissue injury scores for the deltoid muscle (P < .001) and pectoralis muscle (P < .001). No difference in cephalic vein injury was noted between the 2 groups (P > .05). No difference in surgical time was noted. CONCLUSION: The use of a surgical wound protector device in total shoulder arthroplasty did not significantly decrease bacterial colonization of the deep wound. However, soft tissue damage to the deltoid and pectoralis muscle was less severe in the wound protector group. These findings suggest that this device reduces iatrogenic soft tissue injury.

Humans↗
PubMed1995

Prevention of seromas in mastectomy wounds. The effect of shoulder immobilization.

OBJECTIVE: To determine if postoperative shoulder immobilization decreases the incidence of postmastectomy seromas. DESIGN AND SETTING: A prospective randomized trial of three surgeons' experiences at a community hospital. PATIENTS: Thirty-eight patients who underwent modified radical mastectomy from March 1991 through February 1993. MAIN OUTCOME MEASURES: Incidence of postmastectomy seromas and time required for patients to gain 110 degrees of shoulder abduction after surgery. RESULTS: Thirteen (72%) of 18 wounds in the maximum range of motion cohort developed seromas (72%) compared with one (6%) of 17 in the minimum range of motion cohort (P = .0005). The average time required for the patients with maximum range of motion to gain 110 degrees of shoulder abduction was 2.6 weeks, whereas the patients with minimum range of motion required an average of 5.0 weeks (P = .0127). CONCLUSION: Postmastectomy shoulder immobilization significantly decreases the incidence of wound seromas. Although this protocol resulted in a delay in return to normal shoulder mobility, no patients sustained long-term musculoskeletal dysfunction.

Aged↗
PubMed2000

Electrical stimulation for preventing and treating post-stroke shoulder pain.

BACKGROUND: Shoulder pain after stroke is common and disabling. The optimal management is uncertain, but electrical stimulation (ES) is often used to treat and prevent pain. OBJECTIVES: The objective of this review was to determine the efficacy of any form of surface ES in the prevention and / or treatment of pain around the shoulder at any time after stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Review Group trials register and undertook further searches of MEDLINE, EMBASE and CINAHL. Contact was established with equipment manufacturers and centres that have published on the topic of ES. SELECTION CRITERIA: We considered all randomised trials that assessed any surface ES technique (functional electrical stimulation (FES), transcutaneous electrical nerve stimulation (TENS) or other), applied at any time since stroke for the purpose of prevention or treatment of shoulder pain. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected trials for inclusion, assessed trial quality and extracted the data. MAIN RESULTS: Four trials (a total of 170 subjects) fitted the inclusion criteria. Study design and ES technique varied considerably, often precluding the combination of studies. Population numbers were small. There was no significant change in pain incidence (Odds Ratio (OR) 0.64; 95% CI 0.19 to 2.14) or change in pain intensity (Standardised Mean Difference (SMD) 0.13; 95% CI -1.0 to 1.25) after ES treatment compared to control. There was a significant treatment effect in favour of ES for improvement in pain-free range of passive humeral lateral rotation (Weighted Mean Difference (WMD) 9.17; 95% CI 1.43 to 16.91). In these studies ES reduced the severity of glenohumeral subluxation (SMD -1.13; 95% CI -1.66 to -0.60), but there was no significant effect on upper limb motor recovery (SMD 0.24; 95% CI -0.14 to 0.62) or upper limb spasticity (WMD 0.05; 95% CI -0.28 to 0.37). There did not appear to be any negative effects of electrical stimulation at the shoulder. REVIEWER'S CONCLUSIONS: The evidence from randomised controlled trials so far does not confirm or refute that ES around the shoulder after stroke influences reports of pain, but there do appear to be benefits for passive humeral lateral rotation. A possible mechanism is through the reduction of glenohumeral subluxation. Further studies are required.

Electric Stimulation Therapy↗
PubMed2001

Inflamed shoulder structures in polymyalgia rheumatica with normal erythrocyte sedimentation rate.

OBJECTIVE: To investigate the inflammatory involvement of shoulder articular and extraarticular structures in polymyalgia rheumatica (PMR) patients with a normal erythrocyte sedimentation rate (ESR) at diagnosis. METHODS: This was a case-control study. All consecutive, untreated new outpatients diagnosed as having PMR with a normal ESR (<40 mm/hour) during a 6-month period were included in the study (case patients). Controls were 12 consecutive, untreated PMR outpatients with an ESR of >40 mm/hour who were observed after the case patients. Before starting corticosteroid therapy, all case patients and controls underwent bilateral shoulder ultrasonography (US) and magnetic resonance imaging (MRI). US and MRI scans were evaluated independently by two radiologists who were blinded to the reciprocal results. RESULTS: Six case patients (4 men and 2 women) and 12 controls (4 men and 8 women) were studied. Both US and MRI demonstrated bilateral subacromial/subdeltoid bursitis in all 6 case patients and in 11 of the 12 (92%) controls (P not significant [NS]). One control had unilateral bursitis. Glenohumeral joint synovitis was found in 4 of 6 case patients (67%) by MRI and in 3 of 6 case patients (50%) by US (P NS), as well as in 8 of 12 controls (67%) by MRI and in 7 of 12 controls (58%) by US (P NS). Both MRI and US detected biceps tenosynovitis in 5 of 6 case patients (83%) and in 8 of 12 controls (67%) (P NS). The severity of bursitis did not differ significantly between the groups. US was as effective as MRI in detecting inflammatory changes of the shoulder. CONCLUSION: MRI and US studies showed that PMR patients with normal or high ESRs have similar inflammatory shoulder lesions. Moreover, bilateral subacromial/subdeltoid bursitis represents the imaging hallmark in PMR patients with a high or normal ESR. MRI or US of the shoulder may facilitate the proper diagnosis in patients with the typical proximal symptoms of PMR who also have normal ESRs.

Adult↗
PubMed1976

Morphometric affinities of the human shoulder.

To analyze differences between apes and monkeys and the affinities of man, we have studied the shoulder girdle of 327 specimens of anthropoid primates. The scapula, clavicle and humerus are viewed as an integrated functional complex on the basis of 18 measurements. Several varieties of multivariate analysis show that man is clearly closer to other hominoids than to the included monkey taxa (whether terrestrial or arboreal, Old World or New World). The marked shoulder differences between apes and monkeys and similarities between apes and man correlate with the muscular anatomy, which in hominoids allows the motions involved in their locomotion and feeding behavior. As the hominid-pongid correspondence in shoulder morphology is especially detailed regarding the functionally important joint surfaces, it is consistent with a fairly recent period of common ancestry and behavior. No hypothetical evolutionary pathway or ancestral form of the human shoulder need look far beyond the model afforded by extant pongids. In contrast with previous studies on the primate shoulder, these results agree with information accumulationg from other systems--comparative anatomy, primate behavior, and molecular biology-- in suggesting very close relationship between man and extant African pongids.

Animals↗
PubMed2002

Comparison of clinical and patient-based measures to assess medium-term outcomes following shoulder surgery for disorders of the rotator cuff.

OBJECTIVE: To compare different assessments following shoulder surgery for impingement syndrome with or without rotator cuff tear or repair. METHODS: A prospective study of 93 patients was conducted. Standard assessments were performed before, at 6 months, and at 4 years following shoulder surgery using the patient-based Oxford Shoulder Score (OSS), the Medical Outcomes Study Short Form-36 (SF-36) questionnaire, and a surgeon-assessed Constant Shoulder Score. Patients were categorized according to the surgery received in relation to the presence of cuff tears: full repair, partial repair, cuff tear/no repair, no tear/no repair. RESULTS: Most patients (57%) received subacromial decompression for impingement with no cuff tear. This group had the fewest pre- and postoperative symptoms. The category of patients who received only partial repair of a cuff tear had worse scores on all outcome assessments compared with other groups. Patient-based measures were more stable over time than the Constant. CONCLUSION: The shoulder-specific measures had greater sensitivity than the SF-36 in registering significant differences in outcomes between comparison groups at 6 months and 4 years.

Adult↗
PubMed2003

Intraarticular corticosteroids, supervised physiotherapy, or a combination of the two in the treatment of adhesive capsulitis of the shoulder: a placebo-controlled trial.

OBJECTIVE: To compare the efficacy of a single intraarticular corticosteroid injection, a supervised physiotherapy program, a combination of the two, and placebo in the treatment of adhesive capsulitis of the shoulder. METHODS: Ninety-three subjects with adhesive capsulitis of <1 year's duration were randomized to 1 of 4 treatment groups: group 1, corticosteroid injection (triamcinolone hexacetonide 40 mg) performed under fluoroscopic guidance followed by 12 sessions of supervised physiotherapy; group 2, corticosteroid injection alone; group 3, saline injection followed by supervised physiotherapy; or group 4, saline injection alone (placebo group). All subjects were taught a simple home exercise program. Subjects were reassessed after 6 weeks, 3 months, 6 months, and 1 year. The primary outcome measure was improvement in the Shoulder Pain and Disability Index (SPADI) score. RESULTS: At 6 weeks, the total SPADI scores had improved significantly more in groups 1 and 2 compared with groups 3 and 4 (P = 0.0004). The total range of active and passive motion increased in all groups, with group 1 having significantly greater improvement than the other 3 groups. At 3 months, groups 1 and 2 still showed significantly greater improvement in SPADI scores than group 4. There was no difference between groups 3 and 4 at any of the followup assessments except for greater improvement in the range of shoulder flexion in group 3 at 3 months. At 12 months, all groups had improved to a similar degree with respect to all outcome measures. CONCLUSION: A single intraarticular injection of corticosteroid administered under fluoroscopy combined with a simple home exercise program is effective in improving shoulder pain and disability in patients with adhesive capsulitis. Adding supervised physiotherapy provides faster improvement in shoulder range of motion. When used alone, supervised physiotherapy is of limited efficacy in the management of adhesive capsulitis.

Bursitis↗
PubMed2003

Rheumatoid arthritis of the shoulder joint: comparison of conventional radiography, ultrasound, and dynamic contrast-enhanced magnetic resonance imaging.

OBJECTIVE: To determine the role of ultrasound and magnetic resonance imaging (MRI) compared with conventional radiography in the detection of chronic and acute inflammatory manifestations of rheumatoid arthritis (RA) of the shoulder joint. METHODS: Forty-three consecutive patients with known RA prospectively underwent clinical examination, radiography, ultrasound, and MRI of the shoulder joints. Each patient was assigned a clinical/laboratory score consisting of 7 parameters, including measurements of shoulder mobility, the erythrocyte sedimentation rate, and C-reactive protein level. Conventional radiography was standardized and performed in 2 planes. Ultrasound was performed in 10 predefined planes using a 7.5-MHz linear transducer. MRI at 1.5T comprised transverse and oblique coronal T1- and T2*-weighted fast spin-echo, gradient-echo (GRE), and inversion-recovery sequences with a matrix size of up to 512 pixels. A dynamic T1-weighted GRE sequence was acquired with intravenous administration of contrast medium. Erosions were assessed using all 3 imaging techniques on a 4-point scale. Soft-tissue involvement was evaluated according to the presence of synovitis, tenosynovitis, and bursitis on ultrasound and MRI. The results in the study group were compared with those obtained in a control group of 10 patients with shoulder pain. RESULTS: In the study group, erosions of the humeroscapular joint were detected by conventional radiography in 26 patients, by ultrasound in 30 patients, and by MRI in 39 patients; the differences were statistically significant for the comparisons of conventional radiography with MRI and for ultrasound versus MRI (P < 0.0001). Conventional radiography detected 12 erosions of the scapula and MRI detected 15. Synovitis was demonstrated in 12 patients by ultrasound and in 27 patients by MRI (P = 0.0003). Tenosynovitis was observed in 15 patients by ultrasound and in 28 patients by MRI (P = 0.0064). Bursitis was detected in 13 patients by ultrasound and in 18 patients by MRI. The findings on dynamic contrast-enhanced MRI correlated significantly with the detection of synovitis by ultrasound and erosions by static MRI (P < 0.05). CONCLUSION: Ultrasound and MRI supplement conventional radiography in assessing the shoulder joint. Although conventional radiography can be used as the sole method of following up known joint destruction in RA, ultrasound and, preferably, MRI are recommended as additional techniques in the initial diagnostic evaluation when radiography yields negative results.

Adult↗
PubMed1987

Frozen shoulder in hyperthyroidism.

A patient who presented with bilateral frozen shoulders and unrecognized hyperthyroidism is described. Both frozen shoulder and the related shoulder-hand syndrome may occur in this setting. These poorly understood rheumatic conditions often are complications of stroke, spinal cord injury, or diabetes. Dysfunction of the autonomic nervous system is thought to be of pathogenic importance. It is postulated that the close resemblance of hyperthyroidism to activation of the sympathetic nervous system may underlie its association with frozen shoulder and shoulder-hand syndrome.

Diagnosis, Differential↗
PubMed1995

Shoulder range of motion in patients with osteoporosis.

OBJECTIVE: To determine the degree of loss of shoulder flexion in patients with osteoporosis, and to determine whether this was correlated with functional disability and pain as measured by the modified Health Assessment Questionnaire. METHODS: Two different exercise regimens, one using traditional extension exercises of the spine (group A) and the other using both the extension exercises and exercises to stretch and strengthen scapular musculature (group B), were compared to determine their effects on range of motion, pain, and disability in 33 women with osteoporosis. RESULTS: A significant improvement in shoulder flexion occurred in both exercise groups compared to controls; however, there were no statistically significant differences either within or between exercise groups from baseline to study end. A decrease in pain correlated with an increase in shoulder flexion in group A (r = 0.56), while an improvement in functional disability scores correlated with an increase in shoulder flexion in group B (r = 0.46). CONCLUSION: Traditional spinal exercises along with exercises that target scapular mobility help to improve shoulder flexion, pain, and function in women with osteoporosis.

Aged↗
PubMed2003

Lymphoedema and reduced shoulder function as indicators of quality of life after axillary lymph node dissection for invasive breast cancer.

BACKGROUND: The aim was to explore measurements of arm circumference and shoulder abduction as indicators of quality of life after axillary lymph node dissection for invasive breast cancer. METHODS: Differences in arm circumference and shoulder abduction were measured in 465 consecutive women who underwent axillary lymph node dissection. These women received a treatment-specific questionnaire on the severity of physical disability and the effects on their daily life and well-being. RESULTS: The questionnaire was returned by 400 women (86 per cent). Of these 400, only the 332 women who did not receive axillary radiotherapy were included in the analysis. Their mean time since axillary lymph node dissection was 4.2 (range 0.3-28) years. For 86 patients (26 per cent) there was a difference in arm circumference of 2 cm or more, or a difference in abduction of 20 degrees or more. These patients found it more difficult to do household chores, were more likely to have given up hobbies, felt more disabled and were more likely to be treated by a physiotherapist. However, complaints also occurred among the women with smaller differences in arm circumference and shoulder abduction, although the frequency and severity of their complaints were similar to those in women without swelling of the arm or without restricted shoulder abduction. CONCLUSION: Measuring arm circumference and shoulder abduction during control visits identifies only some of the women whose daily life and well-being is affected by the side-effects of axillary lymph node dissection.

Activities of Daily Living↗
PubMed1984

Electromyographic analysis of shoulder muscle load.

The influence of hand tool weight and arm position on shoulder muscle load was studied by electromyography. The investigation was made to facilitate recommendations on work place design. The aim is to reduce the occurrence of occupational shoulder disorders in industry. Nine volunteers held 21 different arm positions with the hand over waist level. In each position, the hand was loaded with 0, 1, and 2 kg. Each load was maintained for 15 s. The myoelectric activity in six shoulder muscles was recorded and analyzed automatically with respect to the amplitude. The results indicate that the degree of upper arm elevation is the most important parameter influencing shoulder muscle load. Short rotator muscles stabilizing the shoulder joint were found to be more hand-load dependent than the deltoid muscle. The ergonomic implications of this study are that work situations should be designed so that the arm can be kept close to the body and the hand load minimized.

Adult↗
PubMed1996

Optimal normalization tests for shoulder muscle activation: an electromyographic study.

To accurately compare electromyographic data from different muscles and different subjects, it is necessary to normalize the integrated data obtained from each muscle. The purpose of this study was to identify the manual muscle testing positions that elicit maximal neural activation (integrated electromyography) of three rotator cuff muscles (supraspinatus, infraspinatus, and subscapularis) and five shoulder synergists (pectoralis major, latissimus dorsi, and anterior, middle, and posterior deltoids). The electromyographic activity of these eight muscles was examined in the nondominant shoulders of nine subjects. Indwelling wire electrodes (supraspinatus, infraspinatus, and subscapularis) and surface adhesive electrodes (pectoralis major, latissimus dorsi, and anterior, middle, and posterior deltoids) were placed. Each subject performed a series of 27 isometric contractions, and optimal tests (maximal neural activation) were identified for each muscle. Four tests were identified that resulted in the maximal neural activation of all eight shoulder muscles: 90 degrees of scapular elevation with -45 degrees of humeral rotation for the supraspinatus, anterior deltoid, and middle deltoid: external rotation at 90 degrees of scapular elevation and -45 degrees of humeral rotation for the infraspinatus and posterior deltoid: internal rotation at 90 degrees of scapular elevation and neutral humeral rotation for the subscapularis and latissimus dorsi: and internal rotation at 0 degree of elevation and neutral rotation for the pectoralis major. These results identify four standard testing positions that will provide reference values for normalization of maximal voluntary contraction for the eight muscles of the shoulder examined in this study. Standardization of these test positions offers normalization guidelines that can be used in future dynamic electromyography studies of the shoulder.

Adult↗
PubMed1999

Effects of isokinetic muscle activity on pressure in the supraspinatus muscle and shoulder torque.

Work-related shoulder pain is an increasing problem. Work in overhead positions, which causes high pressure in the supraspinatus muscle, has been shown to increase the shoulder load. It is not known how different types of muscle activity in the shoulder affect pressure in the muscle. The aim of this study was to investigate the difference between contraction modes. This has not been done before for shoulder muscles. The results are relevant from several aspects, both clinical and experimental. Pressure in the supraspinatus muscle and torque generation in the shoulder during isokinetic concentric and eccentric activity were measured in nine healthy human subjects. Torque and arm position were measured continuously with a computerized ergonometer. The contraction velocity was 60 degrees per second, and the range of movement was 0-120 degrees of abduction. Electromyographic measurements were recorded with a surface electrode above the supraspinatus muscle belly. Intramuscular pressure was recorded with a microcapillary infusion technique. Peak intramuscular pressure did not differ significantly between the two modes of contraction, but the peak was reached at 115 degrees (SD = 15 degrees) of abduction during concentric activity and at 6 degrees (SD = 7 degrees) of abduction during eccentric activity. The ratio between intramuscular pressure and torque was 3.0 mm Hg/Nm (0.40 kPa/Nm) during concentric activity and 2.3 mm Hg/Nm (0.31 kPa/Nm) during eccentric activity. The peak torque occurred at 44 degrees of abduction during concentric muscle activity and at 74 degrees of abduction during eccentric activity. Intramuscular pressure was higher during isometric contraction than during eccentric and concentric activity, and the torque was in between the two latter contraction modes. We conclude that the supraspinatus muscle is heavily loaded not only in high arm positions during concentric contraction but also during eccentric contraction in arm positions of 0-30 degrees of abduction.

Adult↗
PubMed2004

In vivo precision of quantitative shoulder cartilage measurements, and changes after spinal cord injury.

Recent advances in MRI have enabled the quantitative assessment of articular cartilage morphology in human joints. In this study, we tested the hypothesis that the precision of quantitative shoulder cartilage measurements is sufficient to detect changes between and within patients, and that shoulder cartilage thickness in paraplegic patients increases due to increased loading. We imaged the shoulders of seven healthy volunteers four times using a coronal 3D, fat-suppressed, gradient-echo sequence. The humeral head cartilage in seven paraplegic patients was evaluated soon after injury and 1 year post injury. A precision of 4.5% (root mean square (RMS) average coefficient of variation (CV) %) was found for shoulder cartilage thickness measurements in the humeral head. Whereas a significant decrease of cartilage thickness (-11%, P < 0.05) was observed in the knee, there was no significant change in articular cartilage thickness in the shoulder (-1.1%). Our data show, for the first time, that articular cartilage of the humeral head can be quantified with acceptable precision in vivo. It was demonstrated that, in contrast to the knee, the articular cartilage morphology of the humeral head changes very little (i.e., there is no significant increase or decrease in thickness) after spinal cord injury (SCI).

Adaptation, Physiological↗
PubMed1993

Shoulder muscle load and muscle fatigue among industrial sewing-machine operators.

Physiological responses to physical work were assessed for 29 female industrial sewing-machine operators during an 8-h working day under ordinary working conditions. During sewing-machine work, the average (left and right) static load in the trapezius muscle was 9% of the maximal electromyogram (EMG) amplitude (% EMGmax), while the average mean load was 15% EMGmax, and the average peak load was 23% EMGmax. The static load level was unrelated to the muscle strength of the sewing-machine operators, which for the group as a whole was within the normal range. The load levels remained unchanged during the working day, while changes in the EMG mean power frequency and zero crossing frequency rate occurred, both indicating the development of muscle fatigue in left and right trapezius muscle during the working day. In line with this, the rating of perceived exertion in the shoulder and neck region increased during the working day. Dividing the group of sewing-machine operators into two groups, those with the highest frequency and those with the lowest frequency of shoulder/neck troubles showed that the former group had significantly lower muscle strength, despite the fact that no differences in the surface EMG during sewing were found between the two groups. It was concluded that industrial sewing-machine work involves a pattern of shoulder muscle activity which induces fatiguing processes in the shoulder and neck regions. Furthermore, since the static shoulder muscle load was independent of muscle strength, factors other than working posture may be of significance for the static shoulder muscle load.

Adult↗